轻烃球罐焊缝裂纹成因分析及焊接修复技术

Cause analysis and welding repair technology of weld crack of light hydrocarbon spherical tank

针对轻烃球罐在制造安装过程中,母材选择不当、焊缝存在扩散氢、组装内应力、热影响区马氏体含量多等原因造成轻烃球罐赤道带与下极带连接焊缝产生延迟裂纹。文中通过轻烃球罐开罐检验发现裂纹后,采用残余应力检测和金相检验等方法,并追溯母材和焊材力学性能、化学成分等参数以及原施工数据资料,找到裂纹产生的原因,确定消除应力是修复的主要任务,制订了轻烃球罐修复工艺,修正15MnNbR钢球罐的焊后热处理温度为(580±10)℃。经修复后检测各项指标参数,均符合标准要求,对今后轻烃球罐的裂纹处理和修复具有借鉴和指导作用。

In the process of manufacturing and installation of light hydrocarbon spherical tank, delayed crack was produced in the connecting welds between equatorial zone and lower polar zone of light hydrocarbon spherical tank due to improper selection of base metal,diffused hydrogen in welds,internal stress in assembly and high content of martensite in heat affected zone. After the crack was found through the opening inspection of light hydrocarbon spherical tank,the residual stress detection and metallographic inspection were adopted in this paper. The mechanical properties,chemical composition and other parameters of base metal and welding materials and the original construction data were traced to find the cause of the crack,which determined that eliminating the stress was the main task of repair,and the repair technology of light hydrocarbon spherical tank was formulated. The postweld heat treatment temperature of 15Mn NbR spherical tank was corrected to( 580 ± 10) ℃ . After repair,various index parameters tested met the requirements of standards and specifications, which played a reference and guiding role in the crack treatment and repair of light hydrocarbon spherical tank in the future.